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Biomedical subjects

T Kitagami

Publications and source records attributed to T Kitagami.

10 recordsLinked to original sources
PubMed2005

Effects of fluvoxamine on levels of dopamine, serotonin, and their metabolites in the hippocampus elicited by isolation housing and novelty stress in adult rats.

The authors investigated the effects of fluvoxamine on neurochemical changes in the hippocampus elicited by isolation housing and novelty stress. Male F344 rats (11 w) were housed one per cage for four weeks. On each day of the last week (7 days) they were s.c. injected with fluvoxamine (20 mg/kg), and then subjected to novelty stress. Isolation housing significantly increased dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels, whereas fluvoxamine significantly decreased them. Isolation housing significantly increased the DOPAC/DA ratio. Fluvoxamine significantly decreased the DA level, and partially restored the DOPAC and 5-HIAA levels increased by isolation housing.

3,4-Dihydroxyphenylacetic Acid↗
PubMed2004

Fluvoxamine, a selective serotonin reuptake inhibitor, suppresses tetrahydrobiopterin levels and dopamine as well as serotonin turnover in the mesoprefrontal system of mice.

RATIONALE: Tetrahydrobiopterin (BH4) is a coenzyme of tyrosine hydroxylase (TH) and tryptophan hydroxylase (TPH), rate-limiting enzymes of monoamine biosynthesis. According to the monoamine hypothesis of depression, antidepressants will restore the function of the brain monoaminergic system, and BH4 concentration. OBJECTIVE: To investigate the effects of fluvoxamine on BH4 levels and dopamine (DA) and serotonin (5-HT) turnover in the mesoprefrontal system, incorporating two risk factors of depression, social isolation and acute environmental change. METHODS: Male ddY mice (6W) were divided into two housing groups, i.e. group-housing (eight animals per cage; 35 days), and isolation-housing (one per cage; 35 days), SC injected with fluvoxamine (20 or 40 mg/kg; days 29-35), and exposed to 20-min novelty stress (day 35). The levels of BH4, DA, homovanilic acid (HVA), 5-HT, and 5-hydroxyindoleacetic acid (5-HIAA) were measured in the prefrontal cortex and midbrain. RESULTS: Under the group-housing condition, novelty stress significantly increased BH4 levels in both regions, and the HVA/DA ratio in the midbrain, whereas it did not change any parameters in either region under the isolation-housing condition. In the prefrontal cortex, fluvoxamine significantly decreased the 5-HIAA/5-HT ratio under the group-housing condition, and BH4 levels and the HVA/DA ratio under the isolation-housing condition. In the midbrain, fluvoxamine significantly decreased all parameters, except for an increasing in the 5-HIAA/5-HT ratio under the isolation-housing condition. CONCLUSION: Isolation-housing suppressed the increase of BH4 levels and DA turnover elicited by novelty stress. Fluvoxamine suppressed BH4 levels, and DA and 5-HT turnover. Fluvoxamine may have altered DA turnover by suppressing BH4 levels.

Animals↗
PubMed2004

Fluvoxamine, a selective serotonin reuptake inhibitor, suppresses tetrahydrobiopterin in the mouse hippocampus.

In the present study, we investigated the effects of fluvoxamine, a selective serotonin reuptake inhibitor, on brain tetrahydrobiopterin (BH4) levels. We directly measured levels of BH4 by Tani and Ohno's direct method as well as the serotonin (5-HT) turnover ratio, i.e. 5-hydroxyindoleacetic acid (5-HIAA)/5-HT, after sub-acute s.c. injection of fluvoxamine in the hippocampus of mice. Our animal model incorporated two risk factors of depression, social isolation and acute environmental change. Male ddY mice (6W) were housed in isolation (1 per cage; 35 days), injected with fluvoxamine (20 or 40 mg/kg; days 29-35), and exposed to novelty stress (20 min; day 35). In the stress session, behavioral parameters, i.e. total distance and rearing behavior, were measured. Isolation housing increased both behaviors. Fluvoxamine attenuated rearing behavior, but did not influence total distance. Isolation housing increased BH4 levels. Novelty stress increased BH4 levels in group housing, although it did not change them in isolation housing. Fluvoxamine suppressed BH4 levels. In isolation housing, fluvoxamine increased 5-HT turnover ratios, while it decreased them in group housing. In conclusion, fluvoxamine, housing condition, and novelty stress regulated BH4 levels. Fluvoxamine may have changed behavior and 5-HT turnover by suppressing BH4 levels as well as by inhibiting 5-HT reuptake.

Animals↗
PubMed1999

Application of the Zung self-rating depression scale to patients before and after introduction to haemodialysis.

In the present study we applied the Zung self-rating depression scale (SDS) to 19 renal failure patients who were introduced to haemodialysis in the Nagoya Daini Red Cross Hospital, Nagoya, Japan. The patients were divided into two groups: the emergent introduction (EI) group, who underwent unanticipated and sudden introduction to haemodialysis, and the ordinary introduction (OI) group, who experienced a more systematic introduction to haemodialysis following recommendation by medical specialists. The patients' Zung SDS responses were collected twice, just before and 2 weeks after haemodialysis introduction. The total SDS score of the EI group was significantly higher than that of the OI group, both before and after haemodialysis introduction. The total SDS scores for the EI and OI groups were significantly reduced after haemodialysis introduction. The SDS scores for the EI group were significantly higher in the mood of depression and cognitive symptoms categories, both before and after haemodyalysis introduction. Before introduction, SDS scores of the EI group were significantly higher in the categories of motor and vegetative symptoms. The SDS scores for vegetative symptoms in the EI group significantly decreased after introduction to haemodialysis. These results suggest that haemodialytic excretion of uremic toxins helps to reduce SDS scores.

Adaptation, Psychological↗
PubMed1980

Behaviour of teeth under various loading conditions with finite element method.

A study was made of behaviour of the upper central incisor, lower second premolar and lower first molar under various loading conditions, with the finite element method. Analysis was made of tooth deflections, rotational centre, stresses in the periodontal membrane, turning moments of tooth and supporting forces of the periodontal membrane. It was shown that the horizontal vector of load was much more influential to the teeth than the vertical vector, and that effects of the loading angle on the tooth behaviour were found most markedly in the lower first molar, followed by the lower second premolar and upper central incisor in decreasing order.

Dental Stress Analysis↗
PubMed1978

Analysis of stress on a fixed partial denture with a blade-vent implant abutment.

Using a two-dimensional finite element method, a study was made that compared the behavior of a model mandibular posterior fixed partial denture constructed on the second premolar abutment and a blade-vent implant imbedded at the site of the second molar with the behavior of a fixed partial denture constructed on the second premolar and second molar abutments. The following were the results: 1. Deflections of the implant fixed partial denture were less than those of the natural tooth fixed partial denture in vertical and inclined loads. 2. Stress concentration was markedly found in the pontic and the mesial and distal parts of the premolar retainer in both restorations and the implant neck in the implant fixed partial denture. 3. In the implant fixed partial denture, stresses induced in the surrounding bone became higher around the posterior abutment and became lower around the premolar retainer than the stresses produced with the natural tooth fixed partial denture. 4. Therefore it was suggested that, to relieve stress to the surrounding bone around the implant abutment, occlusal forces loaded to the implant fixed partial denture have to be more concentrated on the premolar abutment than do forces loaded to the natural tooth fixed partial denture.

Alveolar Process↗